Method of transferring heat to food articles

ABSTRACT

This invention provides a novel method of and an apparatus for transferring heat to food articles. Basically, the novel method of the present invention comprises: supporting food articles on support means located within a chamber; and forcing a heated liquid heat-transferring medium through means located adjacent to said support means. More specifically, one presently preferred form of the novel method of the present invention involves holding cooked meat food articles at a temperature above 140° F. and within a temperature range of ±5° F. for extended periods without objectionable growth of bacteria within the food articles and without quality deterioration of the food articles, which form a method comprises the steps of: storing cooked meat food articles in a chamber having closure means intended to be repeatedly and frequently opened and closed; supporting said cooked meat food articles on support means located within said chamber; forcing a heated liquid heat-transferring medium through radiator means located adjacent to and on opposite sides of said support means; and maintaining the humidity within said chamber above that of the atmosphere outside of said chamber. Basically, the novel apparatus of the present invention comprises: a chamber; support means for supporting food articles within said chamber; reservoir means for containing a liquid heat-transferring medium; heater means for heating the liquid medium contained in said reservoir means; radiator means located adjacent to said support means; hollow conduit means fluid-connecting said reservoir means and said radiator means; means fluid-connected to said reservoir means and to said radiator means through said hollow conduit means for circulating the liquid medium between said reservoir means and said radiator means; and control means connected to said heater means for controlling to within ±5° F. the desired temperature to which the liquid medium is to be heated and maintained by said heater means.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of Ser. No. 922,230, filed July 5, 1978, now U.S.Pat. No. 4,210,675, which is a continuation-in-part of Ser. No. 835,808,filed Sept. 22, 1977, now U.S. Pat. No. 4,224,862.

BACKGROUND OF THE INVENTION

This invention relates to a method of and an appartus for transferringheat to food articles and, more particularly, to a novel method of andapparatus for such purpose that are particularly adapted for holdingpreviously-cooked food articles quite near to a preferred temperaturefor prolonged time periods, and which can also be employed to initiallycook food articles or to complete the cooking of food articles that havebeen previously partially cooked.

In the past, several forms of old methods and apparatus have beenprovided for attempting to hold previously-cooked food articles near toa preferred temperature, which have been variously commonly referred toas "hot cabinets", "warming safes", "warming receptacles", "food heatingcarts", and "caterers' vehicles".

One recently quite popular form of such prior-art apparatus is marketedby Crescent Metal Products, Inc. of Cleveland, Ohio, as its ModelH-138-CDD-1834 "hot cabinet", and basically comprises a verticallyelongate cabinet or chamber, the exterior of the bottom of which issupported on casters for movement, and the interior of the bottom ofwhich supports an electrically-powered blower that is located closelyadjacent to an electrically-powered heater to thus circulate through thecabinet a heat-transferring medium consisting of heated air, which, inturn, passes over a plurality of horizontally-arranged, verticallyspaced apart food articles supporting trays that are mounted within thecabinet above the blower and the heater. And, the access opening whichextends almost the entire height of the fromt of the cabinet is providedwith closure means that comprise a pair of hinged "dutch doors" for thestated purpose of minimizing the loss of the heated air from the cabinetinterior while access is being obtained. Modified versions of this formof prior-art apparatus are also shown in U.S. Pat. Nos. 3,999,475 and4,010,349, wherein means are also provided for regulating the relativehumidity within the cabinet and transferring water vapor to the foodarticles supported therein which include sump means for containing waterlocated adjacent to the interior of the cabinet bottom and having anopening fluid-connected to the cabinet interior.

With the just-described blower-circulated, electrically-heated air formsof prior-art apparatus, it has been most difficult to maintain foodarticles which are contained within the cabinet anywhere near to thepreferred temperature when the cabinet access doors are opening by theirusers. There has also been considerable temperature variation betweenthose food articles which have been supported in the upper and lowerextremities of the cabinets of such prior-art forms of apparatus, withthose supported lower in the cabinet and closer to the electric heaterbeing kept warmer than those supported higher in the cabinet and, thus,farther away from the heater.

U.S. Pat. Nos. 377,594; 518,042; 1,223,311; 1,752,749; and 3,389,946illustrate alternative forms of such prior-art apparatus wherein eithersteam or heated water, instead of heated air, is utilized for theheat-transferring medium. However, as shown and described in theselast-mentioned five U.S. Patents, all of these additional prior-artforms of apparatus basically differ from the novel apparatus that isprovided in accordance with the present invention, in that none of thoseold apparatus provides any pump means for circulating the steam ofheated water that is employed as the heat-transferring medium between areservoir in which the heat is supplied to the heat-transferring mediumby heater means and radiator means by which the heat is transferred fromthe heat-transferring medium to the food articles that are supportedwithin the cabinet or chamber nor any control means which are connectedto the heater means for controlling to within ± a few °F. the desiredtemperature to which the heat-transferring medium is to be heated andmaintained by the heater means.

Instead of providing pump means, these just-noted steam and heated waterforms of prior-art apparatus rely upon thermal convection to causecirculation of the heat transferring medium between their reservoir andradiator means and, in order to obtain such convective circulation, theheated water or steam must be maintained at or quite near to 212° F.(the boiling point of water). And, since 212° F. is usually more than60° F. higher than the preferred "holding" temperature of most foodarticles, these steam and heated water forms of prior-art apparatus cancause considerable undesired additional cooking or "overcooking" ofcooked food articles which are held therein.

The U.S. Department of Agriculture has long determined that there isconsiderable danger of spoilage and salmonella (food poisoning bacteria)development in food articles which are held for even fairly shortperiods of time at temperatures ranging between 40° F. and 140° F. Quiterecently, that same agency has increased this hazardous temperaturelimit to 145° F. for beef food articles. And, with all of the aforenotedforms of prior-art apparatus, problems have been encountered inattempting to maintain warm food articles held therein at temperaturesabout 140° F. without also causing considerable undesired additionalcooking or "overcooking" of them.

The present invention is directed toward the provision of a novel methodof and an apparatus for transferring heat to food articles, which areparticularly adapted for holding previously-cooked food articles quitenear to a preferred temperature for prolonged time periods andeliminates or greatly mitigates the aforenoted problems that have beenencountered with prior-art apparatus which have been employed in anattempt to achieve that purpose, and which can also be employed toinitially cook food articles or to complete the cooking of food articlesthat have been previously partially cooked.

SUMMARY OF THE INVENTION

The present invention provides a novel method of and an apparatus fortransferring heat to food articles.

Basically, the novel method of the present invention comprises:supporting food articles on support means located within a chamber; andforcing a heated liquid heat-transferring medium through means locatedadjacent to said support means. More specifically, one presentlypreferred form of the novel method of the present invention involvesholding cooked meat food articles at a temperature above 140° F. andwithin a temperature range of ±5° F. for extended periods withoutobjectionable growth of bacteria within the food articles and withoutquality deterioration of the food articles, which form of methodcomprises the steps of: storing cooked meat food articles in a chamberhaving closure means intended to be repeatedly and frequently opened andclosed; supporting said cooked meat food articles on support meanslocated within said chamber; forcing a heated liquid heat-transferringmedium through radiator means located adjacent to and on opposite sidesof said support means; and maintaining the humidity within said chamberabove that of the atmosphere outside of said chamber.

Basically, the novel apparatus of the present invention comprises: achamber; support means for supporting food articles within said chamber;reservoir means for containing a liquid heat-transferring medium; heatermeans for heating the liquid medium contained in said reservoir means;radiator means located adjacent to said support means; hollow conduitmeans fluid-connecting said reservoir means and said radiator means;means fluid-connected to said reservoir means and to said radiator meansthrough said hollow conduit means for circulating the liquid mediumbetween said reservoir means and said radiator means; and control meansconnected to said heater means for controlling to within ±5° F. thedesired temperature to which the liquid medium is to be heated andmaintained by said heater means.

The novel apparatus of the present invention is particularly adapted forholding previously-cooked food articles quite near to a preferredtemperature for prolonged time periods and can also be employed toinitially cook food articles or to complete the cooking of food articlesthat have been previously partially cooked.

The novel apparatus of the present invention is especially adapted fortransferring heat to chicken parts, with the employed liquidheat-transferring medium comprising water. However, it should beunderstood that it also may be utilized to transfer heat to a widevariety of other food articles, such as other meat parts, fish parts,whole vegetables or parts thereof, and the like, wherein water or othersuitable substances are employed for the liquid heat-transferringmedium.

It is desirable that the novel apparatus of the present invention alsoinclude means for regulating the relative humidity within its aforenotedchamber and for transferring water vapor to food articles supportedtherein comprising: sump means having an opening fluid-connected to thechamber for containing water, heating means for heating water containedin the sump means; means for regulating the amount of water that iscontained within the sump means; means for regulating the amount ofwater vapor that passes through the opening from the sump means to thechamber; and vent means for regulating the amount of water vapor thatescapes from the chamber. And, when the employed liquidheat-transferring medium is water, it is further desirable that theaforenoted sump means and heating means for heating water containedtherein respectively also comprise its aforenoted reservoir means andthe heater means for the liquid heat-transferring medium.

It is yet further desirable that the novel apparatus of the presentinvention include temperature sensing means for determining thetemperature of at least one of the food articles that are supportedwithin the aforenoted chamber and additional control means which areconnected to the temperature sensing means and to its aforenoted heatermeans such that the additional control means are operable by thetemperature sensing means to de-energize the heater means when atemperature not greater than 5° F. above a preferred temperature issensed by it and to re-energize the heater means when a temperature notmore than 5° F. below a preferred temperature is sensed by it.

Both the novel method and apparatus of the present invention have beenrigorously tested by the School of Hotel Administration of CornellUniversity of Ithaca, New York, and the highly successful andunexpectedly novel results of those tests have been summarized in atwenty-four page report entitled--DOCUMENTATION OF FOOD TEMPERATURE ANDPRODUCT QUALITY IN THE THERMODYNE CABINET--which was issued by Mr.Joseph F. Durocher of said University with a cover letter dated Mar. 7,1978 to Mr. F. Joseph Scharon, President of Lockwood ManufacturingCompany of Cincinnati, Ohio, my current licensee under the aforenotedco-pending U.S. Pat. Application Ser. No. 835,808, and the entirecontents of which report are hereby wholly incorporated herein byreference. It is to be understood that, in said Cornell report, theterm--Thermodyne cabinet--has been used to designate the form of thenovel apparatus of my present invention which was employed during thetesting reported therein to perform the various forms of the novelmethod of my present invention as reported therein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated in the accompanying drawings,wherein:

FIG. 1 is a somewhat schematic, partly broken, left side elevationalview, including a basic diagrammatic showing of the heater, pump andcontrol means therefor, of a presently preferred form of the novelapparatus that is provided in accordance with the present invention andwhich can be employed to perform various forms of the novel method ofthe present invention;

FIG. 2 is a somewhat reduced fragmentary right front elevationalperspective view of the upper portion of the chamber of the apparatusshown in FIG. 1, but with the upper chamber access door being shown inits open, rather than closed, position and with the drip pan and theoverlying food article supporting rack of each of the illustrated foodarticle support means having been removed from that portion of thechamber;

FIG. 3 is a somewhat enlarged, partly broken, top plan view of one ofthe food article support means and an adjacent one of the radiator meansof the apparatus shown in FIGS. 1 and 2;

FIG. 4 is a greatly enlarged fragmentary left front elevational view,partly in cross-section, of a portion of one of the food article supportmeans and its adjacent radiator means of the apparatus shown in FIGS. 1and 2, with the drip pan and overlying rack for that food articlesupport means being shown installed within the chamber and the chamberaccess door being open; and

FIG. 5 is a greatly enlarged fragmentary left side elevational view ofthe reservoir-sump means and the regulating means therefor of theapparatus shown in FIGS. 1 and 2.

DETAILED DESCRIPTION

Turning now to the drawings and, more particularly, to FIGS. 1-5thereof, there is illustrated a presently preferred embodiment of anovel apparatus 10 that is provided in accordance with the presentinvention for transferring heat to food articles 11 and which can beemployed to perform various forms of the novel method of the presentinvention.

As illustrated, the apparatus 10 comprises: a chamber 12; support means13 for supporting the food articles 11 within that chamber 12; reservoirmeans 14 for containing a liquid heat-transferring medium; heater means15 for heating the liquid medium contained in the reservoir means 14;pump means 16 fluid-connected to the reservoir means 14 and to radiatormeans 17 located adjacent to the support means 13 through hollow conduitmeans 18A, 18B, 18C, 18D, 18E and 18F for circulating the liquid mediumbetween the reservoir means 14 and the radiator means 17; and controlmeans 19 and 19A connected to the heater means 15 for controlling towithin ±5° F. the desired temperature to which the liquid medium is tobe heated and maintained by the heater means 15.

The novel apparatus 10 of the present invention is particularly adaptedfor holding previously-cooked food articles quite near to a preferredtemperature for prolonged time periods and can also be employed toinitially cook food articles or to complete the cooking of food articlesthat have been previously partially cooked.

The novel apparatus 10 of the present invention is especially adaptedfor transferring heat to chicken parts, with the employed liquidheat-transferring medium that is circulated between the reservoir means14 and the radiator means 17 by the pump means 16 comprising water.However, it should be understood that it also may be utilized totransfer heat to a wide variety of other food articles, such as othermeat parts, fish parts, whole vegetables or parts thereof, and the like,wherein water or other suitable substances are employed for thecirculated liquid heat-transferring medium. The food articles 11 mayhave their outer surfaces either uncoated or covered with a coating of afarinaceous material, such as breading, batter and the like.

As further shown in the drawings, the chamber 12 of the apparatus 10comprises the interior of a vertically elongate hollow-walled metalcabinet 12B that has its bottom supported on plural casters 12C formovement and the interior of the bottom of which supports the reservoirmeans 14 and the pump means 16. The cabinet 12B has an access opening12A to the chamber 12 which extends almost the entire height of itsfront and is provided with closure means that comprise a pair of hollowmetal "dutch doors", including an upper door 12U and a lower door 12Dthat are hinged to the right front corner of the cabinet 12B by hinges12H and are respectively provided with handles 12u and 12d. And, thehollow metal cabinet 12B and the hollow metal access doors 12U and 12Dare preferably provided with heat-insulating material between theirinterior and exterior walls to reduce the loss of heat from the chamber12.

As best shown in FIGS. 1 and 5, the reservoir means 14 comprises a tank20 for containing the liquid heat-transferring medium that is to becirculated between it and the radiator means 17 by the pump means 16.And, in the illustrated embodiment of the apparatus 10, wherein thepreferred heat-transferring medium that is to be so circulated is water,this tank 20 has an opening 21 in its top that is fluid-connected to thechamber 12, such that this tank 20 of the reservoir means 14 can alsoserve as sump means for the means that are also provided in theillustrated embodiment of the apparatus 10 for regulating the relativehumidity within the chamber 12 and transferring water vapor to the foodarticles 11 supported therein.

As further shown in FIGS. 1 and 5, water can be supplied to the tank 20of the reservoir-sump means 14 via a float valve 22 that is connected tothe tank 20 from a supply hose 22S that extends through the lowerportion of the right side of the cabinet 12B and can be connected to asource of water (not shown), such as a water faucet of a building inwhich the apparatus 10 is to be employed. The float valve 22 is of awell-known construction and of a type very often utilized in a commodewater storage tank and, in the illustrated embodiment of the apparatus10, serves as means for regulating the amount of water that is containedwithin the tank 20 of the reservoir-sump means 14.

As still further illustrated in FIGS. 1 and 5, a jacketedelectrically-powered heater element 15A of a well-known type is mountedwithin the tank 20 of the reservoir-sump means so as to permit itsimmersion within the water that is to be contained therein. Thus, whenwater is employed as the liquid heat-transferring medium which iscirculated between the reservoir means 14 and the radiator means 17 bythe pump means 16, the heater element 15A serves both as the heatermeans 15 for heating the circulated liquid heat-transferring mediumcontained in the combined reservoir-sump means 14 and also as heatingmeans for heating humidifying water contained therein.

As additionally shown in FIGS. 1 and 5, means, comprising a set ofinterlinked plural louvers 23 that are pivotally connected across theopening 21 through the top of the tank 20 of the reservoir-sump means14, are provided for regulating the amount of water vapor that passesupwardly by convection through that opening 21 to the chamber 12. Asbest illustrated in FIG. 5, these louvers 23 are constructed to beadjustably set by a common operating lever 23L in a variety of positionsranging between minimum closure (FIG. 1) and maximum closure (FIG. 5) ofthe opening 21.

And, as best shown in FIG. 2, vent means, comprising a pair of louveredcircular vents 24 which extend through the upper portion of the upperaccess door 12U, are provided for regulating the amount of water vaporthat escapes from the chamber 12 of the apparatus 10.

As shown in FIGS. 1-4, the support means 13 for supporting the foodarticles 11 within the chamber 12 comprise a plurality of metal shelves13. Each such support means shelf 13 is made of a heat-conductive metaland is provided adjacent the front and rear ends of its upwardly bentleft and right edges with eyes 13E that are selectively engageable witha plurality of vertically spaced-apart hooks 13H which are provided on apair of bracket means 13B that are affixed adjacent to the front andrear ends of the interior left and right side walls of the cabinet 12Band extends vertically from just above the aforenoted opening 21 in thetop of the tank 20 for the combined reservoir-sump means 14 to alocation somewhat below the top of the chamber 12. With thisarrangement, the plural support means shelves 13 can be generallyhorizontally mounted within the chamber 12 and selectively verticallyspaced apart from one another therein by a variety of distances to thusaccommodate various sizes of food articles 11. And, for each suchsupport means shelf 13, there is also provided a drip pan 13D to restatop of it together with an overlying rack 13R therefor upon which thefood articles 11 are, in fact, seated.

As further illustrated in FIGS. 1 and 3-4, the radiator means 17 of theapparatus 10 comprise plural sections of hollow tubing. Each suchradiator means tubing section 17 is made of a highly heat-radiative andheat-conductive material, such as copper, aluminum or the like, and hasbeen bent into a serpentine configuration between its inlet end 17a andits outlet end 17b. As shown, the bottom of each one of the aforenotedsupport means shelves 13 has affixed to it the top surface of one suchserpentine radiator means tubing section 17. And, as furtherillustrated, each such radiator means tubing section 17 has its inletend 17a and its outlet end 17b provided with coupling means such that itcan be quickly fluid-connected in series with another like it or withone of the aforenoted hollow conduit means 18D or 18E which fluidconnect the radiator means 17 with the reservoir means 14 and the pumpmeans 16. With this arrangement, as best shown in FIG. 1, the foodarticles 11 can be supported on each support means shelf 13 within thechamber 12 with the heat being transferred to them by the radiator meanstubing sections 17 that will thus be located adjacent to and on oppositesides (upper and lower) of each such support means shelf 13.

As yet furhter illustrated in FIGS. 1 and 5, the pump means 16preferably comprises a centrifugal-type pump that is driven by anelectrically-powered motor 16A. While various forms of such pumps may beutilized, good results have been obtained when employing one marketed bythe Goulds Company that has a 1/2 horsepower motor to pump water at aflow rate of one gallon per minute at a discharge pressure of 30p.s.i.g. The pump means 16 has its inlet or suction fluid-connected bythe hollow conduit means 18A to an opening 14A that is provided in thelower portion of the tank 20 of the reservoir means 14. And, the outletor discharge of the pump means 16 is fluid-connected to the inlet end17a of the lowermost one of the aforedescribed radiator means tubingsections 17 via hollow conduit means 18B, 18C and 18D, with thedischarge of the circulated liquid heat-transferring medium from theoutlet end 17b of the uppermost one of the aforenoted radiator meanstubing sections 17 being returned to the upper portion of the tank 20 ofthe reservoir means 14 through the conduit means 18E and 18F.

As basically diagrammatically shown in FIG. 1, the electrically-poweredheater means 15 and the electrically-powered drive motor 16A for thepump means 16 are connected in electrically parallel across anelectrical-power source that is illustrated as lines L₁ and L₂, and anormally-open manually-operable "main" electrical switch 25 is providedfor simultaneously electrically disconnecting and/or connecting bothrespectively from and to the source of electrical power.

As further basically diagrammatically shown in FIG. 1, one of the twoelectrical terminals of the electrically-powered drive motor 16A for thepump means 16 is electrically connected to one of the two electricalpower lines L₁, down-circuit of the "main" switch 25, through aconductor 26 and a manually-operable normally-open electrical switch 27and the other electrical terminal of the pump means drive motor 16A iselectrically connected to the other electrical power line L₂ through aconductor 28.

As yet further basically diagrammatically shown in FIG. 1, one of thetwo electrical terminals of the electrical heater means 15 iselectrically connected to one of the two electrical power lines L₁down-circuit of the "main" switch 25 through a conductor 29 and amanually-operable normally-open electrical switch 30 and the otherelectrical terminal of the electrical heater means 15 is electricallyconnected to the other electrical power line L₂ through a conductor 31,the normally-closed thermally-actuatable switch 19 of the control means19 and 19A, another conductor 32, another normally-closedthermally-actuatable switch 33 of a second control means 33 and 33A andyet another conductor 34.

The actuator of the switch 19 for the first of the aforenoted controlmeans 19 and 19A is connected to and is operable by a firsttemperature-sensing means 19A that is mounted within the lower portionof the tank 20 of the combined reservoir-sump means 14 to sense thetemperature of the liquid heat-transferring medium that is containedtherein. The temperature at which the actuator of the switch 19 will beoperated to open the switch 19 can be selectively manually adjusted bythe operator of the novel apparatus 10 of the present invention. Forexample, when the employed circulated liquid heat-transferring medium iswater and the food articles 11 are previously-cooked, coated chickenparts, this desired temperature may be 170° F. It is most desirable thatthe first of the aforenoted control means, which are comprised of theswitch 19 and the temperature-sensing means 19A, be capable ofcontrolling the operation (electrical energization and de-energization)of the heater means 15 so as to control the temperature of the liquidheat-transferring medium that is heated thereby to within not greaterthan ±5° F. (and, preferably, to within not greater than ±2° F.) of thedesired temperature to which the liquid heat-transferring medium is tobe heated and maintained by the heater means 15. For this purpose, goodresults have been obtained by employing for the switch 19 and itstemperature-sensing actuator means 19A a control means that is sold asModel No. FD-10-CF-RP by Fenwal, Inc. of Ashland, Massachusetts U.S.A.

And, the actuator of the normally-closed thermally-actuatable switch 33by the second control means 33 and 33A is connected to and operable by asecond temperature-sensing means 33A that is mounted within the chamber12 and can be inserted into at least one of the food articles 11supported therein by the support means 13 to sense the interiortemperature thereof. The temperature at which the actuator of the switch33 will be operated to open the switch 33 also can be selectivelymanually adjusted by the operator of the novel apparatus 10 of thepresent invention to a preferred temperature. This preferred temperatureis the temperature which the operator wants to achieve and/or maintainat the center of the food article 11 into which the secondtemperature-sensing means 33A is inserted. When the apparatus 10 isemployed to initially cook food articles or to complete the cooking offood articles that have been previously partially cooked, this preferredtemperature is the so-called "doneness temperature" of the food article11, e.g. for chicken parts, this "doneness temperature" is 186° F.; forbeef parts, at least 145° F.; and for fish parts, 174° F. However, itshould be understood that it is often preferred to hold food articleswhich have been previously fully cooked at a "holding temperature" thatis lower than their "doneness temperature". Hence, it should be furtherunderstood that this preferred temperature for causing operation of theactuator of the switch 33 may be either the aforenoted "donenesstemperature" or the aforenoted "holding temperature".

OPERATIONS

As previously noted above, the novel apparatus 10 of the presentinvention is particularly adapted for holding previously-cooked foodarticles quite near to a preferred temperature for prolonged periods oftime. However, it can also be employed to initially cook food articlesor to complete the cooking of food articles that have been previouslypartially cooked. In any event, the following initial procedure isfollowed in utilizing the novel apparatus 10 of the present invention.

First, the operator opens both of the access doors 12U and 12D to thechamber 12 and installs the food article support means shelves 13 andthe radiator means tubing sections 17 within the cabinet, with thevertical spacing between them being arranged to accommodate theparticular size of the food articles 11 to which heat is to betransferred by operation of the apparatus 10. This, of course is done byhooking the eyes 13E of each such support means shelf 13 overappropriate ones of the hooks 13H that are provided on the brackets 13Bwithin the chamber 12 and by fluid-connecting in series the inlet 17aand outlet 17b ends of the adjacent radiator means tubing sections 17.And, the fluid-connections are also made between the inlet end 17a ofthe lowermost such radiator means tubing section 17 and the hollowconduit member 18D and between the outlet end 17b of the uppermost oneof such radiator means tubing section 17 and the hollow conduit member18E.

Next, the operator connects the supply hose 22S to a source ofpressurized water, such as a water faucet of the building in which theapparatus 10 is to be employed, and also electrically connects theapparatus 10 to a suitable source of electrical power.

Then, the operator inspects the tank 20 of the reservoir-sump means 14to assure that it has been filled with a sufficient amount of water toimmerse the heater element 15A through proper operation of the floatvalve 22.

Next, the operator manually adjusts the thermally-actuatablenormally-closed electrical switches 19 and 33 to respectively providethe desired and the preferred opening temperatures therefor and alsomanually adjusts the operating lever 23L for the louvers 23 into thenecessary position to regulate to the desired percentage the relativehumidity within the chamber 12.

Then, the operator manually closes, first, the two normally-openmechanical operable electrical switches 27 and 30 and then, the "main"electrical switch 25, thus energizing the heater means 15 and the pumpmeans 16.

The remaining steps that are to be performed by its operator inutilizing the novel apparatus 10 of the present invention, of course,vary, depending on whether it is to be used as "holding cabinet" forholding previously-cooked food articles quite near to a preferredtemperature or, alternatively, as a "cooker" to initially cook foodarticles or to complete the cooking of food articles that have beenpreviously partially cooked. Hence, these remaining operational stepsare hereinafter described for each of these particular usages of thenovel apparatus 10 of the present invention.

Holding Cabinet Operation

To use the apparatus 10 as a "holding cabinet" the operator next closesboth of the chamber access doors 12U and 12D and allows the heater means15 sufficient time to raise the temperature in the chamber 12 to thepreferred temperature at which it is desired to hold thepreviously-cooked food articles 11. Assuming 62° F. tap water is usedfor the circulated liquid heat-transferring medium and the preferredtemperature is that for holding previously-cooked, coated chicken foodarticles (150° F.), this will require several minutes.

After the preferred "holding temperature" has been sensed by the sensingmeans 33A as having been reached and continuing to be maintained withinthe chamber 12, the apparatus 10 is now ready to receive and "hold" thepreviously-cooked food articles 11.

Then, at a location outside of the chamber 12, such food articles 11 areseated on the plural racks 13R which, of course, are rested atop theirrespective drip pans 13D.

Next, the chamber access doors 12U and 12D are opened by the operatorand the food article bearing assembled racks 13R and drip pans 13D aremanually inserted by the operator into the chamber 12 to be horizontallysupported therein by the support means shelves 13.

The access doors 12U and 12D are, of course, closed as soon as thesupport means shelves 13 adjacent to them have been loaded with thejust-noted food article bearing assemblies of racks 13R and drip pans13D. However, prior to that, the sensing means 33A is inserted into thecenter of one of the food articles 11.

Once the above-described steps have been performed by the operator ofthe novel apparatus 10 of the present invention, the pump means 16 willremain energized to continue circulating the liquid heat-transferringmedium between the reservoir means 14 and the radiator means 17. And,the heater means 15 will remain energized, until either the firsttemperature-sensing means 19A senses that the desired temperature towhich the liquid heat-transferring medium is to be heated (typically 20°F. higher than the preferred temperature at which the food articles 11are to be held) has been reached and, then, causes the normally-closedthermally-actuatable adjustable electric switch 19 to open, or until thesecond temperature-sensing means 33A senses that the preferredtemperature at which the food articles 11 are to be held (the "holdingtemperature") has been reached and, then, causes the secondnormally-closed thermally-actuatable adjustable electric switch 33 toopen. These two thermally-actuatable switches 19 and 33 will,thereafter, be intermittently re-closed and re-opened by theirrespective temperature-sensing means 19A and 33A to cause suchintermittent re-energization and de-energization of the heater means 15as is necessary to either maintain the temperature of the liquidheat-transferring medium at within no more than ±5° F. (and, preferably,to within ±2° F.) of that desired or to maintain the temperature atwhich the food articles 11 are held at within no more than ±5° F. (and,preferably, to within ±2° F.) of the preferred "holding temperature."

With this arrangement, the "held" food articles 11 will be locatedwithin the chamber 12 of the novel apparatus 10 of the present inventionon the support means shelves 13 with one of the radiator means tubingsections 17 being located closely adjacent to and on opposite side (theupper and lower sides, as illustrated) of each such support means shelf13. Hence, there will be little, if any, temperature variation betweenthose food articles 11 which are "held" in the upper and lower portionsof the chamber 12. And, perhaps even more importantly, such openings ofthe chamber access doors 12U and 12D as will be required, from time totime, to remove some of the "held" food articles 11 from the chamber 12,for services to a consumer thereof, will cause only very little, if any,temporary decrease in the temperature of the remaining "held" foodarticles 11 which continue to be retained within the chamber 12.

Cooker Operation

When using the novel apparatus 10 of the present invention as a"cooker", rather than as a "holding cabinet", its operator need notnecessarily wait for the heating means 15 to raise the sensedtemperature within the chamber 12 to the preferred "donenesstemperature", e.g. 186° F. for uncoated chicken parts, before insertingthe as yet not fully cooked food articles 11 therein.

Instead, the operator may, at a location outside of the chamber 12, seatthe as yet not fully cooked food articles 11 on the plural racks 13Rwhich, of course, are rested atop their respective drip pans 13D andmanually insert into the chamber 12 the food article bearing assembledracks 13R and drip pans 13D to be horizontally supported therein by thesupport means shelves 13 any time after he has completed the last one ofthe aforedescribed initial procedure steps.

Then, the access doors 12U and 12D are, of course, closed just as soonas the support means shelves 13 adjacent to them have been loaded withthe just-noted food article bearing assemblies of racks 13R and drippans 13D. However, prior to that, the sensing means 33A is inserted intothe center of one of the food articles 11.

Once this last-described step has been performed by the operator of thenovel apparatus 10 of the present invention, the pump means 16 willremain energized to continue circulating the liquid heat-transferringmedium between the reservoir means 14 and the radiator means 17. And,the heater means 15 will remain energized, until either the firsttemperature-sensing means 19A senses that the desired temperature towhich the liquid heat-transferring medium is to be heated (typically 20°F. higher than the preferred "doneness temperature" of the food articlesto be cooked) has been reached and, then, causes the normally-closedthermally-actuatable adjustable electric switch 19 to open, or until thesecond temperature-sensing means 33A senses that the food articles 11have reached and are being maintained at the prefered "donenesstemperature", and, then, causes the second normally-closedthermally-actuatable adjustable electric switch 33 to open. These twothermally-actuatable switches 19 and 33 will, thereafter, beintermittently re-closed and re-opened by their respectivetemperature-sensing means 19A and 33A to cause such intermittentre-energization and de-energization of the heater means 15 as isnecessary to either maintain the temperature of the liquidheat-transferring medium at within no more than ±5° F. (and, preferably,to within ±2° F.) of that desired or to achieve and maintain thetemperature at which the food articles 11 are to be cooked at within nomore than ±5° F. (and, preferably, to within ±2° F.) of their particularpreferred "doneness temperature".

Of course, once the operator of the novel apparatus 10 of the presentinvention observes that the sensing element 33A has indicated that thepreferred "doneness temperature" for the food articles 11 has beenreached and is being maintained, the operator may, then, cause theapparatus 10 to operate as a "holding cabinet" by manually resetting theadjustable normally-closed thermally-actuatable switch 33 such that itsactuator will, thereafter, be operated when the temperature senses bythe sensing element 33A equals a preferred "holding temperature" for thenow fully-cooked food articles 11, which "holding temperature" isusually quite a bit lower than the "doneness temperature" (some 36° F.lower, in the case of chicken parts, which have a preferred "donenesstemperature" of 186° F. and a preferred "holding temperature" of 150°F.). And, at this same time, the operator preferably also manuallyresets the adjustable normally-closed thermally-actuatable switch 19such that its actuator will be operated when the temperature sensed byits sensing element 19A equals a desired temperature that is typically20° F. above the desired "holding temperature" for the now fully-cookedfood articles 11.

The following are examples of preferred "doneness temperatures" whichmust be achieved and maintained for at least two minutes in order tofully cook the food articles 11 with the novel apparatus 10 of thepresent invention: fowl 186° F.; "medium-done" beef 155° F.; "well-done"beef 165° F.; pork 176° F.; and fish 174° F.

The preferred "holding temperature" at which the novel apparatus 10 ofthe present invention is particularly adapted to maintain the foodarticles 11 for prolonged periods of time ranges between 142° F. and152° F.

And, the amount of water vapor that is transferred to the food articles11 which can be both "cooked" and "held" by the novel apparatus 10 ofthe present invention can, of course, be controlled by regulating thepercentage of relative humidity within its chamber 12 through selectedpositioning of the operating lever 23L for the louvers 23 that arepivotally mounted across the opening 21 atop its sump means 14, to thuscontrol the "moistness" or "dryness" of those food articles 11 to aparticularly preferred degree.

It should be apparent to those skilled in the art that while there hasbeen described what presently is considered to be a presently preferredembodiment of this invention in accordance with the Patent Statutes,changes may be made in the disclosed method and apparatus withoutactually departing from the true spirit and scope of this invention. Itis therefore intended that the appended claims shall cover suchmodifications and applications that may not depart from the true spiritand scope of the present invention.

What is claimed is:
 1. A method of transferring heat to food articlescomprising:(a) supporting food articles on support means located withina chamber; (b) mechanically forcing circulation of heated liquid waterthrough radiator means at a flow rate of approximately one gallon perminute for transferring heat to the food articles, said radiator meansbeing located in the upper portion of said chamber adjacent to and onopposite sides of said support means and being fluid-connected viahollow conduit means to sump means for containing said liquid water thatare located in the lower portion of said chamber beneath said supportmeans such that said liquid water is both withdrawn from and returned tosaid sump means by said circulation thereof, with the water being heatedin said sump means; (c) maintaining the humidity within said chamberabove that of the atmosphere outside of said chamber by heating thewater so as to produce water vapor in said sump and controlling theamount of water vapor that is first transferred from said sump means tosaid chamber and, subsequently, vented from said chamber to theatmosphere by operation of means for controlling flow through an openingthat is provided between said sump means and said chamber and byoperation of vent means provided for said chamber; and (d) maintainingsaid heated liquid water at a temperature of within ±5° F. of a desiredtemperature by directly heating said liquid water with heater meanslocated within said sump means.
 2. A method of transferring heat to foodarticles comprising:(a) supporting food articles on support meanslocated within a chamber; (b) mechanically forcing circulation of heatedliquid water through radiator means for transferring heat to the foodarticles, said radiator means being located in the upper portion of saidchamber adjacent to and on opposite sides of said support means andbeing fluid-connected via hollow conduit means to sump means forcontaining said liquid water that are located in the lower portion ofsaid chamber beneath said support means such that said liquid water isboth withdrawn from and returned to said sump means by said circulationthereof, with the water being heated in said sump means; (c) maintainingthe humidity within said chamber above that of the atmosphere outside ofsaid chamber by heating the water so as to produce water vapor in saidsump and controlling the amount of water vapor that is first transferredfrom said sump means to said chamber and, subsequently, vented from saidchamber to the atmosphere by operation of means for controlling flowthrough an opening that is provided between said sump means and saidchamber and by operation of vent means provided for said chamber; and(d) maintaining said heated liquid water at a temperature of within ±5°F. of a desired temperature by directly heating said liquid water withheater means located within said sump means.
 3. The invention of claim2, wherein said heated liquid water is circulated under pressure betweensaid sump means and said radiator means through said hollow conduitmeans fluid-connecting said sump means and said radiator means by pumpmeans that are fluid-connecting to said sump mean and said radiatormeans through said hollow conduit means.